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2006 4.3l overheated

M

mcfam

New member
I purchased a 2006 mercruiser 4.3l over the winter and started using it for my 1st season. The 1st time out it would get hot at idle and it ran around 180 -200 degrees. I flushed the motor with muffs and water came out clean and lots of it. It also vapor locked once on the 1st trip, but was able to get it started. 2nd trip was taking out to the beach on the 2nd day and it got hot idling into beach so I shut it off and let it sit for awhile. it vapor locked again and took the starter out this time before I could get it started. I then checked the oil and it was over full but looked clean and in great shape. brought it home and decided to drain some oil, but I couldn't figure out where the over fill had come from. It was water in the bottom of the pan. So I have a gasket leaking somewhere. I was going to do a cylinder test for he head gasket and I was wondering if someone could walk me through doing a air test? I have never done one on a motor with out a radiator. I have found out thermostat was wrong it has a 180 in it when it should have a 160,but the impeller was changed last year so what else can I check for the overheating at idle problem ?
 
Couple of things don't make sense. you bought it without a water test and supposedly winterized. You were using it and noticed it ran hot.Shut it off and hydro-locked it and took out the starter. Then discovered the high oil level that you say was clean.
Now you drain plain water from the bottom of the crankcase.
That means the water entered from a hydro-lock and you never ran it to mix the oil and water.So go with a blown head gasket
first. pull the heads and examine the gaskets and cylinders for and cracks.
Then pull the lower and replace the impeller to make sure its a new one.
 
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The boat was a friends. he took me out in it last season and it had no problems. He is the original owner, he winterized it and had to sell it this winter so I purchased it. When I got it the only thing I needed to do this season was change the oil, so I know it was filled right and done. The impeller and other maintance he did last year. He also had the thermostat put in but didn't know either that they had in a 180. So that bring up to now. Yes, the water was clean. Do I need to go straight to the head gasket or could it come from somewhere else? The boat never ran bad either time.
 
to have a lot of clean water not mixed with the oil has to come from a leak when the motor was not running.
head gasket,cracked head, cracked block, cracked manifold.
Start by removing the thermostat and examining the intake manifold floor for a hole or crack
Then drain the manifolds seeing if one is already empty ,thats the bad one.
Remove the heads and the valves and inspect heads or have them inspected.
Inspect cylinder bore with the piston all the way down.
Given enough time ,water will run past the rings pretty easily
 
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ok, I was afraid of that. It only sucks water when it is running so how did it get in there when it wasn't running?
 
I pulled the thermostat housing out and what is the bolt with the balls on it for? It attaches to the exhaust hoses. Is there a setting for it and if so what?
 
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